Sylvania



Feb. 19, 1929.

F. S. STICKNEY HIGH VOLTAGE INSTRUMENT Filed Sept. 16

INVENTOR P6777010 S S Tic/h1 WITNESSES:

AT'TORNEY srArss EERIIALID F3. STICKNEY, 0F PITTSBURGH, YENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC 8: MANUFACTURING COMPANY,

SYLVANIA.

Application filed September 16, 1926.

My invention relates to high-voltage instruments and particularly to instrui'nents that are subjected directly to high voltages up to a maximum of approximately $1100 volts.

One object of my inve; ion is to provide an instrument, of the above indicated character, that shall be self protected againsthigh voltages.

Another object of my invention is to provide a high-voltage instrument that shall be comparable in appearance and size to forme instruments that were adapted for similar service but were capable of withstanding relatively small Voltages only.

Another object of my invention is to provide a high-voltage instrument that shall embody metal parts similar to certain of the metal parts of former instruments to thereby insure strength and durability of the structure but that shall have insulating parts so combined therewith and substituted for other parts as to materially improve the instrument.

A further object of my invention is to provide an instrument that shall be simple in construction, economical to manufacture and effective in its operation.

Tn practicing my invention, I provide a casing comprising a metal side-wall structure, an insulating sleeve therefor, a base member having a countersunk portion and a perimetral surface-creepage barrier, an annular metal member for securing the base member to the sidewall structure, an instrument mechanism and a dial plate that are so constructed and related to each other as to enable the device to withstand voltages of relatively high values in a more effective manner than former similar instruments of which I am aware.

Fig. 1 of the accompanying drawings is.

A CLRPORATIOH OF PENN- HIGH-VOLTAGE 1N STRUMEN '31.

{serial No. 135,951.

wall structure 1, an insulating sleeve member 4, a plurality of retaining members 5 for the sleeve 4, a window member 7, an instrument mechanism 8, terminal means 9 therefor and studs 10 for mounting the olevioe on an instrument panel or similar structure.

The sidewall structure 1 is preferably constructed of relatively thin sheet metal having a forward perimetral flange 11 against which the window member 7 rests and an annular rear portion 12 of greater diameter than the main body portion thereof to provide an annular shoulder 14.

The base member 2 constitutes a relatively thick discoidal insulating element having a countersunk front face portion 16 for supporting the instrument mechanism 8 and providing a perimetral barrier portion 1'? to effect a relatively great surface-creepage distance between the nearest metal parts on the countersunk portion 16 and the annular member 3.

The member 3 is preferably of metal and constructed as a ring or annular member having offset-plane portions 19 and 20 which respectively fit against the shoulder 14 and the rear surface of the base member 2 adjacent to the perimeter thereof. The member 3 is secured to the base member 2 by screws 21 and to the shoulder 1% by screws 22. An annular felt or similar member 2a provides a dust-proof seal between the shoulder 14 and the portion 19 of the member 3.

The sleeve 4 is preferably constructed as a relatively short cylinder of thin sheet fibrous insulating material impregnated with a hardening binder, such as bakelite-micarta, and conforms closely to the interior surface of the side wall of the member 1 between the window member 7 and the ring 5. The

members 5 are preferably of metal and soldered to the side wall member 1 to hold the sleeve 4 and the window member 7 in position.

The instrument mechanism 8 is of a usual and well known type constituting no special part of my invention and. comprises, in general, a permanent-magnet member 26 that is secured in the countersunk portion 16 in the base member 2, as by brackets 25, and is procoil or bobbin 29 is pivotally supported in a bearing-bridge structure 30 of usual construction and carries a pointer 32 that is biased to Zero position by a spring 33 and cooperates with a scale 34: on a dial plate 35.

The dial plate 35 is of considerably smaller diameter than the side-wall member 1 to provide effective clearance with respect thereto and is supported on the brackets 27 and on a standard 36 that is also secured to the countersunk portion 16 on the insulating base member 32, as by a screw 37.

The studs 10 are yieldably secured to the ring 3, as by stirrups 38, to permit lateral adjustment of the free ends thereof to openings in a panel or other device on which the instrument is to be mounted.

In the above described structure, there are no direct metallic conducting paths from the terminal means 9, the instrument mechanism 8 and the dial plate 35 to the metal ring 3 or to the metal side-wall structure 1. The

I insulating sleeve 1- prevents flash-over from the dial and instrument-mechanism to the side-Wall member 1.

The countersunk portion 16 of the base member 2 provides a relatively long surfacecreepage distance from the instrument and dial parts to the annular metal member 3.

My invention provides an instrument that is simple and rugged in construction and that operates effectively in connection with relatively high-voltage circuits without damage to the instrument or danger to a user.

While I have shown and described a particular form of my invention, changes may be effective therein without departing from the spirit and scope thereof, as set forth in the appended. claims.

1 claim as my invention:

1. In combination, in an electrical instrument, a metal side-Wall structure having portions of different diameter to provide an annular shoulder, an insulating base member, an annular metal member having on?- set-plane portions cooperating with said shoulder and said base member to secure the base member to the side-wall structure, and an annular dust-proofing element between said shoulder and said annular metal member.

2.111 combination, in an electrical instrument, a metal side-wall structure having portions of different diameters to provide an annular shoulder, an insulating base member having a countersunk instrument SUPPOitlDP' portion providing: a surfacecreepage barrier therearound, an annular metal having offset-plane portions cooperating with said shoulder and said base member to secure the base member to the sidewall structure, and means providing a dustproof joint between said annular metal member and the side-wall structure.

3. In combination, in an electrical instrument, a metal side-Wall structure having portions of different diameter to provide an annular shoulder, an insulating base member having a countersunk instrument-supportportion providing a surtace-creepage barrier therearound, an annular metal member having offset-plane portions cooperating with said shoulder and said base memher to secure the base member to the sidewall structure, dust-proofing ring between said annular metal member and said shoulder, an insulating sleeve constituting a lining for said side-wall structure, a dial plate disposed in spaced relation to said countersunk portion and to said insulating sleeve, and means projecting from said countersunk portion to said dial plate for supporting the latter.

in testimony whereof, I have hereunto subscribed my name this 13th day of September, 1926.

FERNALD S. STICKNEY. 

